Performance of two solar cooking storage pots using parabolic dish solar concentrators during solar and storage cooking periods with different heating loads

Abstract

A comparative experimental study on the effect of different cooking loads for two solar cooking pots incorporated with different thermal energy storage (TES) materials is presented. The pots have cavities in their walls for placing TES materials and are designed to be used with parabolic solar cookers. One pot is filled with erythritol as the TES material in the cavity, while the cavity of the other pot is filled with sunflower oil as the TES material. During the solar cooking period, the storage pots are heated up with solar energy, and cooking occurs as well as storage of thermal energy in the cavities of the pots. During the storage cooking period, the pots are placed in wonderbag slow cookers for off-sunshine cooking using the stored heat in the cavities. Water and sunflower oil with masses of 0.5,1.0, 1.5, 2.0, and 2.5 kg, respectively, are used as the cooking loads during both solar and storage cooking periods. The effect of the load is evaluated in terms of storage and heat utilisation efficiencies. The storage efficiencies marginally increase with the increase in the load when water is used as the heating load. The sunflower oil pot shows slightly higher storage efficiencies (3.2–4.4%) compared to the erythritol pot (2.5–3.9%) with water as the cooking load. Storage efficiencies using sunflower oil as the cooking load show slightly greater values compared to when using water and follow no particular trend with the increase in the mass of the load. Heat utilisation efficiencies increase with the load for both storage cooking pots and both cooking fluids. However, water shows higher heat utilisation efficiencies (erythritol-13-49%, sunflower oil-17-46%) compared to sunflower oil (erythritol-9.2–19%, sunflower oil-9.4–28%) during the heat utilisation experiments. The erythritol storage pot shows higher heat utilisation efficiencies compared to the sunflower pot when using water as the heating fluid. However, when using sunflower oil as the heating fluid, the sunflower oil pot shows higher heat utilisation efficiencies.